Cobalt cordierites

FIGURE 3.9 Linewaver-Burke plots of 1A vs. 1/c, from rotating disk voltammograms recorded for OC (squares) and p (rhombs) cobalt cordierite-modified glassy carbon electrodes (GCEs) in contact with a 1.25 mM mannitol plus 1.0 M NaOH aqueous solution. Potential scan rate. 50 mV/sec. 

The observed response (Figure 6.18) can be attributed to the superposition of vol-tammetric responses for octahedrally coordinated Co + ions (broad peak at -0.65 V) and tetrahedrally coordinated Co + centers (peaks at -0.38 and -0.58 V). For a cobalt cordierite, the cathodic process in acidic media can be described as a reductive dissolution/metal deposition ... 

For magnesium-cobalt cordierites, however, the electrochemical process can be represented as a partial dissolution of cobalt centers with concomitant coordinative rearranging ... 

Domenech, A., Torres, RJ., and Alarcon, J. 2004d. Electrochemical characterization of cobalt cordierites attached to paraffin-impregnated graphite electrodes. Journal of Solid State Electrochemistry 8, 127-137. 

There has been a considerable effort in the physics and chemistry communities to use INS methods to study magnetic dynamics, which can often be described as spin waves. Measurements of spin wave dispersion curves can provide information about the interactions between atomic magnetic moments, the so-called exchange interactions. There have been comparatively few INS measurements on magnetic minerals. INS methods have been used to produce spin wave dispersion curves for hematite. Crystal field magnetic transitions in cobalt bearing cordierite, and spinel phases have also been studied by INS. ... 

FIGURE 6.17 Cyclic voltammograms for (a) cobalt-, and (b) nickel-glass cordierites attached to paraffin-impregnated graphite electrodes immersed into 1 M HCl. Potential scan rate 20 mV/sec. Materials courtesy of Prof. Javier Alarcon, University of Valencia. 

Cordierite monoliths were coated with an alumina washcoat and stabilised at 550°C. Some of the samples were then immersed in either an aqueous solution of cerous or cobalt nitrate, dried and calcined in air at 550°C at which the metal nitrates decomposed into their oxides [11]. The samples were weighed and the procedure was repeated until 40 mg of the metal oxide had been deposited onto the alumina washcoated monolith samples. Pt and Pd were applied by direct impregnation using aqueous solutions of HaPtCla and PdCb followed by diying and calcination in air at 550°C [8]. The Pt and Pd loadings (2.0 and 1.09 mg, respectively) of the catalysts were equal on molar basis. The nominal composition of the eight catalysts prepared are listed in Table 1. 

Rodrigues CP, da Silva VT, Schmal M. Partial oxidation of ethanol over cobalt oxide based cordierite monolith catalyst. Appl Catal B Environ. 2010 96 1. 

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